Back to EveryPatent.com
United States Patent |
5,589,099
|
Baum
|
December 31, 1996
|
Low foaming rinse agents comprising ethylene oxide/propylene oxide block
copolymer
Abstract
Ethylene oxide/propylene oxide block copolymers having high cloud points,
when compared to conventional rinse agent materials, have surprisingly
been found to be useful in the manufacture of effective low foaming rinse
aids. The rinse aids are prepared by combining the high cloud point
copolymer with an effective defoamer and a water miscible diluent. The
rinse aid composition can achieve adequate rinsing at common aqueous rinse
temperatures at a concentration of the block copolymer in water less than
500 parts of the block copolymer per million parts of water. A liquid
rinse agent concentrate can take the form of a low viscosity liquid, a
thickened pourable or semi-pourable aqueous liquids. A solid rinse agent
concentrate can be a cast solid material packaged within a soluble or
disposable wrapper or capsule or other water soluble package. The rinse
aids can be dispersed in a variety of ways by dilution with water to an
aqueous final rinse composition. The uniqueness of the invention relates
to the fact that all components are not expected to be active as sheeting
agents and are approved as food additives thereby eliminating any health
concerns associated with residual deposits of the composition on cleaned
ware.
Inventors:
|
Baum; Burton M. (Mendota Heights, MN)
|
Assignee:
|
Ecolab Inc. (St. Paul, MN)
|
Appl. No.:
|
049973 |
Filed:
|
April 20, 1993 |
Current U.S. Class: |
510/514; 510/221 |
Intern'l Class: |
C11D 001/66 |
Field of Search: |
252/174.15,174.21,108,174.18
|
References Cited
U.S. Patent Documents
4618446 | Oct., 1986 | Haslop et al. | 252/135.
|
4793943 | Dec., 1988 | Haslop et al. | 252/135.
|
4871467 | Oct., 1989 | Akred et al. | 252/135.
|
5045225 | Sep., 1991 | Aronson et al. | 252/174.
|
5073298 | Dec., 1991 | Gentle et al. | 252/358.
|
5133892 | Jul., 1992 | Chun et al. | 252/90.
|
5152933 | Oct., 1992 | Holland | 252/559.
|
Foreign Patent Documents |
0000216 | Jan., 1979 | EP.
| |
0182461 | May., 1986 | EP.
| |
1807782 | Jun., 1979 | DE.
| |
49-126703 | Dec., 1974 | JP.
| |
50-62211 | May., 1975 | JP.
| |
51-68608 | Jun., 1976 | JP.
| |
86-131272 | Jun., 1986 | JP.
| |
86-161193 | Jul., 1986 | JP.
| |
59-187096 | Jun., 1990 | JP.
| |
Other References
"Rinse Additives for Machine Dischwashing", Wilson et al., Soap and
Chemical Specialties, pp. 48 et seq. (Feb. 1958).
|
Primary Examiner: Pal; Asok
Assistant Examiner: Irzinski; E. D.
Attorney, Agent or Firm: Merchant, Gould, Smith, Edell, Welter & Schmidt
Claims
We claim:
1. A food grade rinse agent composition comprising approved food additive
ingredients, suitable for dilution to form an aqueous rinse, the
composition comprising:
(a) about 5 to 40 wt-% of a nonionic block copolymer composition,
comprising ethylene oxide and propylene oxide, having a molecular weight
between 10,000 and 15,000 and a cloud point, measured using a 1 wt-%
aqueous solution, greater than 100 .degree. C.;
(b) about 0.2 to 25 wt-% of a food additive defoamer composition; and
(c) up to about 95 wt-% of a water soluble diluent composition.
2. The composition of claim 1 wherein the composition is a liquid
concentrate comprising 60 to 95 wt-% water.
3. The composition of claim 1 wherein the nonionic block copolymer has the
formula:
(EO).sub.x -(PO).sub.y -(EO).sub.z
wherein x is 30 to 130, y is 15 to 70, z is 30 to 130 and x+y is
.gtoreq.60.
4. The composition of claim 1 wherein the defoamer comprises a silicone
defoamer.
5. The composition of claim 4 wherein the silicone defoamer comprises a
combination polydimethylsiloxane and silica at a ratio of about 5 to 100
parts by weight of a polydimethylsiloxane per each part by weight of
silica.
6. The composition of claim 1 wherein the defoamer comprises a fatty acid
defoamer.
7. The composition of claim 6 wherein the fatty acid aleroamer comprises a
fatty acid ester of glycerol.
8. The composition of claim 7 wherein the fatty acid ester is a mono fatty
acid ester of glycerol.
9. The composition of claim 1 wherein the defoamer comprises an alkali or
alkaline earth metal salt of a fatty acid.
10. A liquid food grade rinse agent composition comprising approved food
additive ingredients, suitable for dilution to form an aqueous rinse, the
composition comprising:
(a) about 5 to 40 wt-% of a nonionic block copolymer composition, having
the formula (EO).sub.x (PO).sub.y (EO).sub.z with a molecular weight
between 10,000 and 15,000, wherein x is 30 to 130, y is 30 to 70, z is 30
to 130 and x+y is .gtoreq.60, having a cloud point, measured with a 1 wt-%
aqueous solution, greater than 100.degree. C.;
(b) about 0.5 to 20 wt-% of a defoamer selected from the group consisting
of a polydialkylsiloxane and a fatty acid ester of glycerol;
(c) about 0.05 to 1 wt-% of a water soluble carboxylic acid compound; and
(d) about 40 to 95 wt-% of a water.
11. The composition of claim 10 wherein the water soluble carboxylic acid
comprises benzoic acid, sorbic acid or mixture thereof.
12. The composition of claim 10 wherein the composition also comprises a
0.1 to 1.0 wt-% of a thickener.
13. A cast solid food grade rinse agent composition, suitable for dilution
to form an aqueous rinse, the composition comprising:
(a) about 1 to 25 wt-% of a nonionic block copolymer composition, having
the formula:
(EO).sub.x (PO).sub.y (EO).sub.z
with a molecular weight between 10,000 and 15,000, wherein x is 30 to 130,
y is 30 to 70, z id 30 to 130 and x+y is .gtoreq.60, having a cloud point,
measured with a 1 wt-% aqueous solution, of greater than 100.degree. C.;
(b) about 1 to 25 wt-% of a food additive defoamer composition; and
(c) about 5 to 80 wt-% of a water soluble casting agent diluent.
14. The composition of claim 13 wherein the casting agent comprises a
polyalkylene glycol.
15. The composition of claim 13 wherein defoamer comprises a silicone
defoamer.
16. The composition of claim 15 wherein the defoamer cemprises a
combination of polydimethylsiloxane and silica at a ratio of about 1 to
200 parts by weight of a polydimethylsiloxane per each 100 parts by weight
of a silica gel.
17. The composition of claim 13 wherein the defoamer comprises a fatty acid
defoamer.
18. The composition of claim 17 wherein the fatty acid defoamer comprises a
metallic salt of a fatty acid.
19. The composition of claim 17 wherein the fatty acid defoamer comprises a
fatty acid ester of glycerol.
Description
FIELD OF THE INVENTION
The invention relates to warewashing processes and chemicals used in
washing cookware, dishware and flatware. More particularly, the invention
relates to primarily organic materials that can be added to water to
promote a sheeting action in an aqueous rinse used after an alkaline
detergent cycle. Such aqueous rinse aids promote effective sheeting to
result in removal of aqueous rinse materials and solids contained therein
from cookware, dishware and flatware and are low foaming and non-toxic. A
decidedly added benefit is to have the rinse aid composed of materials
that are approved as additives to food.
BACKGROUND OF THE INVENTION
Mechanical warewashing machines have been common in the institutional and
household environments for many years. Such automatic warewashing machines
clean dishes using two or more cycles which can include initially a wash
cycle followed by a rinse cycle. Such dishwashers can also utilize soak
cycle, prewash cycle, scrape cycle, second wash cycle, a rinse cycle, a
sanitizing cycle and a drying cycle, if required. Such cycles can be
repeated if needed and additional cycles can be used. After passing
through a wash, rinse and dry cycle, dishware, cups, glasses, etc., can
exhibit spotting that arises from the uneven draining of the water from
the surface of the ware after the rinse step. Spotting is aesthetically
unacceptable in most consumer and institutional environments.
In order to substantially prevent the formation of spotting rinse agents
have commonly been added to water to form an aqueous rinse which is
sprayed on the dishware after cleaning is complete. The precise mechanism
through which rinse agents work is not established. One theory holds that
the surfactant in the rinse aid is absorbed on the surface at temperatures
at or above its cloud point, and thereby reduces the solid-liquid
interfacial energy and contact angle. This leads to the formation of a
continuous sheet which drains evenly from the surface and minimizes the
formation of spots. Generally, high foaming surfactants have cloud points
above the temperature of the rinse water, and, according to this theory,
would not promote sheet formation, thereby resulting in spots. Moreover,
high foaming materials are known to interfere with the operation of the
warewashing machine. Common rinse aid formulas are used in an amount of
less than about 1,000 parts preferably less than 500 parts, commonly 50 to
200 parts per million of active materials in the aqueous rinse. Rinse
agents available in the consumer and institutional markets comprise liquid
or solid forms which are typically added to, dispersed or dissolved in
water to form an aqueous rinse. Such dissolution can occur from a rinse
agent installed onto the dish rack. The rinse agent can be diluted and
dispensed from a dispenser mounted on or in the machine or from a separate
dispenser that is mounted separately but cooperatively with the dish
machine.
Many rinse agents comprise a polyalkylene oxide copolymer preferably
ethylene oxide/propylene oxide block copolymer. In such materials, the
ethylene oxide block tends to be hydrophilic while the propylene oxide
blocks tend to be hydrophobic producing a separation of hydrophilic and
hydrophobic groups on the surfactant molecule. Those skilled in the art of
formulating nonionic based rinse agents have formed a belief that an EO/PO
block copolymer must have a cloud point (measured in a 1 wt-% aqueous
solution) substantially less than the use temperature of the aqueous rinse
and exhibit good wetting properties to obtain sheeting. Such belief is
borne out in a review of promotional material related to low cloud point
block copolymers. Block copolymers suggested for use in aqueous rinse aids
typically comprise low molecular weight (less than about 5,000) and
display low cloud points (less than about 40.degree. C. using a 1 wt-%
aqueous solution). The common belief in the rinse aid art is that high
cloud point, high molecular weight block copolymers would not exhibit good
sheeting properties and would have substantial foaming problems. Further,
a substantial need has arisen for environmentally compatible rinse agent
compositions. Rinse additives are well known to the trade and have been in
use for thirty or more years. However there is an unmet need for rinse
additives that are made entirely of food additive materials. Formulation
of successful compositions using the limited range of materials approved
as food additives is a very challenging situation since using only food
additive materials greatly limits what can be used in the formulation.
Further, such formulations are very unique in that few combinations will
work.
Surprisingly, we have found that high molecular weight, high cloud point
materials can be effectively defoamed with effective food additive
defoamer materials to form rinse additives which yield desirable
continuous sheets on the ware and provide an extra degree of safety if
they leave any residue on the cleaned ware. In our research on developing
rinse agents, we find that the nonionic agents of the invention are
surprisingly good sheeting agents even though they have high cloud points
and generate significant volumes of foam in use. Those skilled in the art
find that surfactants in rinse aids require both effective wetting agent
properties and low foaming properties. Traditionally, rinse agents contain
nonionic surfactants with relatively low cloud points since these
materials exhibit little foam above the cloud point. The nonionics of the
invention have cloud points above 100.degree. C. measuring a 1 wt-%
aqueous solution and were consistently considered to be poor candidates
for rinse agents because high cloud points indicate poor sheeting
properties. However, we have found surprisingly that although these
materials foam significantly, they have acceptable sheeting properties at
approximately 200 parts, preferably 100 parts, of the nonionic polyether
per million parts of rinse composition. Moreover, we have found that the
use of certain classes of defoamers in combination with the nonionics of
the invention yield rinse agent materials with very low foaming properties
that perform very well in sheeting tests. We have found food additive
defoamers that can be combined with food additive nonionic block copolymer
materials. Most high foaming nonionic materials are generally hydrophilic
and quite water soluble. On the other hand, adequate defoaming materials
tend to be quite hydrophobic. Hydrophilic and hydrophobic materials are
generally incompatible at high concentrations in a concentrated form. In
many warewashing apparatus, defoaming materials are often added directly
to the rinse aid or other aqueous compositions at the point of use. The
defoamer not only suppresses the foaming nature of the high cloud point
nonionic material but appears to make the nonionic material behave like
the low cloud point material in forming an evenly draining, continuous
film. This property of the combination is unexpected. The rinse agents can
be diluted to form an effective aqueous rinse with a water miscible
aqueous diluent. The rinse agents of the invention can also take the form
of a liquid rinse agent or a cast solid rinse agent material.
Haslop et al., U.S. Pat. No. 4,618,446, teaches a variety of ingredients
for use in spherical liquid detergent compositions.
Haslop et al., U.S. Pat. No. 4,793,943, teaches a variety of ingredients
useful for making liquid detergent compositions.
Akred et al., U.S. Pat. No. 4,871,467, teaches a variety of compositions
and materials used to form non sedimenting liquid detergent compositions.
Aronson et al., U.S. Pat. No. 5,045,225, teaches a combination of
hydrocarbon oils and silicone compositions as antifoam materials.
Gentle et al., U.S. Pat. No. 5,073,298, teaches silicone silicate based
defoaming compositions.
Chun et al., U.S. Pat. No. 5,133,892, teaches machine dishwashing detergent
tablets having timed release of enzyme and chlorine bleach and a variety
of other ingredients used in making the detergent composition.
Tsukada, Japanese Patent Application Publication Kokai 49-126,703, teaches
carbohydrate aliphatic ester rinse agents.
Miura et al., Japanese Patent Application Publication Kokai 50-62,211,
teaches polyhydric alcohol containing rinse agents.
Miura et al., Japanese Patent Application Publication Kokai 51-68,608,
teaches polyol aliphatic ester containing rinse agent compositions.
Suzuki et al., Japanese Patent Application No. 86-131,272, teaches a rinse
agent comprising a polyethoxylated sorbitan fatty acid ester glycerol and
a sugar alcohol.
Suzuki et al., Japanese Patent Application No. 86-161,193, teaches a
similar material.
Nantaku, Japanese Patent Application No. 59-187,096, teaches a
polyglycerine ester of a C.sub.6-8 fatty acid containing rinse agent.
Wilson et al., "Rinse Additives for Machine Dishwashing", Soap and Chemical
Specialties, pp 48 et seq. (February 1958), discusses the basic technology
regarding rinse agent formulation.
None of the prior art material combine the preferred high cloud point, high
foaming surfactants with an appropriate defoamer to achieve a rinse agent
that can be diluted into an aqueous rinse providing low foaming sheeting
properties.
BRIEF DISCUSSION OF THE INVENTION
The invention resides in part in a concentrated, low foaming, effective
rinse agent composition formulated from food additive components which can
take the form of a dilutable liquid, gel or solid concentrate. The minimum
requirement for a concentrated rinse agent is effective sheeting action
and low foam in an aqueous rinse. Such concentrate materials may contain a
nonionic block copolymer and a defoamer composition to provide basic rinse
requirements. Such materials can contain an ethylene oxide-propylene oxide
nonionic block copolymer with a high cloud point. The nonionic block
copolymer can commonly comprise compounds produced by polymerizing
ethylene oxide and propylene oxide.
Illustrative but non-limiting examples of various suitable high cloud point
nonionic surface active agents for the rinse agents of this invention
include polyoxyethylene-polyoxypropylene block copolymers having the
formula:
(EO).sub.x (PO).sub.y (EO).sub.z
wherein x, y and z reflect the average molecular proportion of each
alkylene oxide monomer in the overall block copolymer composition. x
typically ranges from about 30 to 130, y typically ranges from about 30 to
70, z typically ranges from about 30 to 130, and x plus y is typically
greater than about 60. The total polyoxyethylene component of the block
copolymer constitutes typically at least about 40 mol-% of the block
copolymer and commonly 75 mol-% or more of the block copolymer. The
material preferably has a molecular weight greater than about 5,000 and
more preferably greater than about 10,000.
An important characteristic of the nonionic block copolymers used in the
rinse agents of the invention is the cloud point of the material. The
cloud point of nonionic surfactant of this class is defined as the
temperature at which a 1 wt-% aqueous solution of the surfactant turns
cloudy when it is heated.
BASF, a major producer of nonionic block copolymers in the United States
recommends that rinse agents be formulated from nonionic EO-PO sheeting
agents having both a low molecular weight (less than about 5,000) and
having a cloud point of a 1 wt-% aqueous solution less than the typical
temperature of the aqueous rinse. The prevailing understanding of the
skilled artisan in this area is that a nonionic surfactant with a high
cloud point or high molecular weight would either produce unacceptable
foaming levels or fail to provide adequate sheeting capacity in a rinse
aid composition.
As disclosed in the BASF literature, wetting ability is another important
factor in choosing a block copolymer as a rinse aid. Good wetting
properties lead to spot and film free glassware, "wetting increases with
increasing hydrophobe molecular weight and decreasing hydrophile weight."
The block copolymer of this invention are highly hydrophilic and not
considered good wetting agents. They would not, consequently, be
considered good candidates for rinse additives. The uniqueness of the
invention relates to the fact that all components are not expected to be
active as sheeting agents and are approved as food additives thereby
eliminating any health concerns associated with residual deposits of the
composition on cleaned ware.
There are two general types of rinse cycles in commercial warewashing
machines. A first type, a sanitizing rinse cycle, uses rinse water at
about 180.degree. F. (about 80.degree. C.). A second type in
non-sanitizing machines use lower temperature non-sanitizing rinse water.
Typically, the temperature of the service water available, from the water
heaters installed at the use location, is about 125.degree. F. (about
50.degree. C.), 140.degree. F. (about 60.degree. C.), 160.degree. F.
(about 70.degree. C.), etc. A surfactant useful in any of these use
locations is an aqueous rinse having a cloud point greater than the
available hot service water. Accordingly, the lowest useful cloud point,
measured using a 1 wt-% aqueous solution, for the nonionics of the
invention point is approximately 40.degree. C. The cloud point can be
60.degree. C., 70.degree. C., 80.degree. C. or 90.degree. C., depending on
the use locus water temperature.
For the purpose of this invention, the term "rinse agent" includes
concentrate materials that are diluted with an aqueous stream to produce
an aqueous rinse. Accordingly, an aqueous rinse agent is an aqueous
material that is contacted with ware in a rinse cycle. A sheeting agent is
the polymeric material used to promote the even drainage of the aqueous
rinse. Sheeting is defined as forming a continuous, evenly draining film,
leaving virtually no spots or film upon the evaporation of water. For the
purpose of this invention, the term "dish" or the term "ware" is used in
the broadest sense of the term to refer to various types of articles used
in the preparation, serving, consumption, and disposal of food stuffs
including pots, pans, trays, pitchers, bowls, plates, saucers, cups,
glasses, forks, knives, spoons, spatulas, and other glass, metal, ceramic,
plastic composite articles commonly available in the institutional or
household kitchen or dining room.
Defoaming agents (defoamers) include a variety of different materials
adapted for defoaming a variety of compositions. Defoamers can comprise an
anionic or nonionic material such as polyethylene glycol, polypropylene
glycol, fatty acids and fatty acid derivatives, fatty acid sulfates,
phosphate esters, sulfonated materials, silicone based compositions, and
others.
Preferred defoamers are food additive defoamers including silicones and
other types of active anti-foam agents. For the purposes of this
application, the term "food additive" means materials listed in the U.S.
Code of Federal Regulations 21 Part 172--Food Additives Permitted for
Direct Addition to Food for Human Consumption, 21 Part 182--Substance
Generally Recognized as Safe and 21 Part 184--Direct Food Substances
Affirmed as Generally Recognized as Safe, and 21 Part 173--Secondary
Direct Food Additives Permitted in Food for Human Consumption, Section
173.310--Defoaming Agents.
Silicone foam suppressors include polydialkylsiloxane preferably
polydimethylsiloxane. Such silicone based foam suppressors can be combined
with silica. Such silica materials can include silica, fumed silica,
derivatized silica, silanated silica, etc. Commonly available anti-foaming
agents combines a polydimethylsiloxane and silica gel. Another food
additive defoaming agent comprises a fatty acid defoamer. Such defoamer
compositions can comprise simple alkali metal or alkaline earth metal
salts of a fatty acid or fatty acid derivatives. Examples of such
derivatives include mono, di- and tri- fatty acid esters of polyhydroxy
compounds such as ethylene glycol, glycerine, propylene glycol, hexylene
glycol, etc. Preferably such defoaming agents comprise a fatty acid
monoester of glycerol. Fatty acids useful in such defoaming compositions
can include any C.sub.8-24 saturated or unsaturated, branched or
unbranched mono or polymeric fatty acid and salts thereof, including for
example myristic acid, palmitic acid, stearic acid, behenic acid,
lignoceric acid, palmitoleic acid, oleic acid, linoleic acid, arachidonic
acid, and others commonly available. Other food additive anti-foam agents
available include water insoluble waxes, preferably microcrystalline wax,
petroleum wax, synthetic petroleum wax, rice base wax, beeswax having a
melting point in the range from about 35.degree. to 125.degree. C. with a
low saponification value, white oils, etc. Such materials are used in the
rinse agents of the invention at a sufficient concentration to prevent the
accumulation of any measurable stable foam within the dish machine during
a rinse cycle.
The food grade rinse aid composition of the invention can contain one or
more solid water soluble food grade fillers for the purpose of
facilitating processing, product stability, or dispensing of the
composition or contributing to other performance characteristics. Many
different types of fillers may be utilized in the rinse agent composition,
including specifically but not limited to such compounds as a sugar such
glucose, fructose, sucrose; an alkali metal salt such as sodium chloride,
potassium chloride, sodium carbonates, sodium bicarbonate, sodium sulfate,
potassium sulfate, sodium acetate, sodium lactate, water soluble amino
acids such as alanine, arginine, glycine, lysine, proline; phosphates such
as tetrasodium pyrophosphate, sodium phosphate and others.
The rinse agents of the invention can contain a complexing or chelating
agent that aids in reducing the harmful effects of hardness components in
service water. Typically calcium, magnesium, iron, manganese, and other
polyvalent metal cations, present in service water, can interfere with the
action of either washing compositions or rinsing compositions. A chelating
agent can effectively complex with and prevent such ions from the service
water interfering with the action of an active component increasing rinse
agent performance. Both organic and inorganic chelating agents are common.
Inorganic chelating agents include such compounds as sodium pyrophosphate,
and sodium tripolyphosphate. Organic chelating agents include both
polymeric and small molecule chelating agents. Polymeric chelating agents
commonly comprise ionomer compositions such as polyacrylic acids
compounds. Small molecule organic chelating agents include salts of
ethylenediaminetetracetic acid (EDTA) and hydroxyethylenediaminetetracetic
acid, nitrilotriacetic acid, ethylenediaminetetrapropionates,
triethylenetetraminehexacetates, and the respective alkali metal ammonium
and substituted ammonium salts thereof. Amino-phosphates are also suitable
for use as chelating agents in the composition of the invention and
include ethylenediamine tetra(methylenephosphonates),
nitrilotrismethylenephosphonates, diethylenetriaminepenta(methylene
phosphonates). These amino phosphonates commonly contain alkyl or alkylene
groups with less than 8 carbon atoms. Preferred chelating agents for this
invention include approved food additive chelating agents such as the
disodium salt of ethylenediaminetetracetic acid.
The liquid rinse agent compositions of the invention have a liquid base
component which functions as a carrier and cooperates with aqueous
diluents to form the aqueous rinse. Liquid bases are preferably water or a
solvent compatible with water to obtain compatible mixtures thereof.
Exemplary nonlimiting solvents in addition to water include a low
molecular weight C.sub.1-6 primary and secondary mono, di- and tri-
hydroxy alcohol such as methanol, ethanol, isopropanol, and polyols
containing from two to six carbon atoms and from two to six hydroxyl
groups such as propylene glycol, ethylene glycol, glycerine, propane diol,
propylene glycol, etc.
The organic nature of the rinse agents of the invention can be subject to
microbial and chemical decomposition. Organic materials are commonly
useful in stabilizing the mixtures. Preferred preservatives or stabilizers
for the invention include food grade stabilizers, food grade antioxidants,
et cetera. Most preferred materials for use in stabilizing the
compositions of the invention include C.sub.1-10 mono, di- and
tricarboxylic acid compounds. Preferred examples of such acids include
acetic acid, citric acid, benzoic, sorbic, lactic, maleic, tartaric and
fumaric.
Optional ingredients which can be included in the rinse agents of the
invention in conventional levels for use include solvents, hydrotropes,
processing aids, corrosion inhibitors, dyes, fillers, optical brighteners,
germicides, pH adjusting agents (monoethanolamine, sodium carbonate,
sodium hydroxide, hydrochloric acid, phosphoric acid, et cetera),
bleaches, bleach activators, perfumes and the like.
The compositions of the invention can be formulated using conventional
formulating equipment and techniques. The compositions of the invention
typically can comprise proportions as set forth in Table I.
In the manufacture of the liquid rinse agent of the invention, typically
the materials are manufactured in commonly available mixing equipment by
charging to a mixing chamber the liquid diluent or a substantial
proportion of a liquid diluent. Into a liquid diluent is added
preservatives or other stabilizers. Care must be taken in agitating the
rinse agent as the formulation is completed to avoid degradation of
polymer molecular weight or exposure of the composition to elevated
temperatures. The materials are typically agitated until uniform and then
packaged in commonly available packaging and sent to distribution center
before shipment to the consumer.
TABLE I
______________________________________
Liquid Rinse Agent Proportions
Useful Preferred
Most Preferred
______________________________________
Nonionic 0.1-50 5-40 10-30
Sheeting Agent
Defoamer 0.1-30 0.2-25 1-15
Thickener 0-5 0-4 0.1-1
Preservative
0-1 0.01-0.5 0.025-0.2
Diluent Balance Balance Balance
______________________________________
The liquid materials of the invention can be adapted to a cast solid format
by incorporating into the composition a casting agent. Typically organic
and inorganic solidifying materials can be used to render the composition
solid. Preferably organic materials are used because inorganic
compositions tend to promote spotting in a rinse cycle. The most preferred
casting agents are polyethylene glycol and an inclusion complex comprising
urea and a nonionic polyethylene or polypropylene oxide polymer.
Polyethylene glycols (PEG) are used in melt type solidification processing
by uniformly blending the sheeting agent and other components with PEG at
a temperature above the melting point of the PEG and cooling the uniform
mixture. An inclusion complex solidifying scheme is set forth in Morganson
et al., U.S. Pat. No. 4,647,258.
The solid compositions of the invention are set forth in Table II as
follows:
TABLE II
______________________________________
Solid Rinse Agent Proportions (wt-%)
Useful Preferred
Most Preferred
______________________________________
Nonionic 0.1-50 5-40 10-30
Sheeting Agent
Defoamer 0.1-30 0.2-25 1-15
Thickener 0-5 0-4 0.1-1
Preservative
0.001-1 0.01-0.5 0.025-0.2
Solidifying
0-25 0.1-15 0.5-0
System
Diluent Balance Balance Balance
______________________________________
Liquid rinse agents of the invention are typically dispensed by
incorporating compatible packaging containing the liquid material into a
dispenser adapted to diluting the liquid with water to a final use
concentration wherein the active material is present in the aqueous rinse
at a concentration of 20 to 500 parts of the active block copolymer per
million parts of the aqueous rinse. More preferably the material is
present in the aqueous rinse at a concentration of about 30 to 300 parts
of the block copolymer per million parts of the aqueous rinse most
preferably the material is present at a concentration of about 40 to 200
parts of the block copolymer per million parts of the aqueous rinse.
Examples of dispensers for the liquid rinse agent of the invention are
DRYMASTER-P sold by Ecolab Inc., St. Paul, Minn. Cast solid products may
be conveniently dispensed by inserting a cast solid material in a
container or with no enclosure into a spray-type dispenser such as the
volume SOL-ET controlled ECOTEMP Rinse Injection Cylinder system
manufactured by Ecolab Inc., St. Paul, Minn. Such a dispenser cooperates
with a warewashing machine in the rinse cycle. When demanded by the
machine, the dispenser directs a spray of water onto the cast solid block
of rinse agent which effectively dissolves a portion of the block creating
a concentrated aqueous rinse solution which is then fed directly into the
rinse water forming the aqueous rinse. The aqueous rinse is then contacted
with the dishes to affect a complete rinse. This dispenser and other
similar dispensers are capable of controlling the effective concentration
of the active block copolymer in the aqueous rinse by measuring the volume
of material dispensed, the actual concentration of the material in the
rinse water (an electrolyte measured with an electrode) or by measuring
the time of the spray on the cast block.
The following examples and data further illustrate the practice of the
invention, should not be taken as limiting the invention and contains the
best mode. The following examples and data show the effectiveness of the
invention in promoting adequate rinsing and shows that the claimed
defoamers in cooperation with the claimed nonionic block copolymers with a
high cloud point in combination provide effective rinsing and sheeting
action on dishware when used. Further, the data show a variety of
well-known defoamers in combination with the block copolymers of the
invention fail to provide defoaming and sheeting action.
EXAMPLE 1
Into an appropriately sized glass beaker equipped with a mechanical mixer
is placed 85 parts of filtered deionized water. Agitation is begun and to
the beaker is added about 13 parts by weight of a nonionic, EO.sub.x
PO.sub.y EO.sub.z (wherein x is 128, y is 54 and z is 128) surfactant
having a cloud point of greater than about 100.degree. C. (Pluronic F108)
slowly, until dissolution is complete. Then into the nonionic solution is
added two parts by weight of sodium oleate. The mixture is agitated until
uniform. The final pH was 8.6.
EXAMPLE 1A
Using the procedure of Example 1, the following formulation was prepared
using a nonionic surfactant (Pluronic F108) having a cloud point of
>100.degree. C. at 13.0 wt-%. A polydimethylsiloxane/silica defoamer at
6.5 wt.-% 1.3% active, a xanthan thickener at 0.25 wt.-%, benzoic acid at
0.05 wt.-%, sorbic acid 0.10 wt.-5, tap water 80.10 wt.-%. Final pH 3.6
(adjusted with HCl).
EXAMPLES 2A AND B
Into a suitably sized glass beaker equipped with a mechanical mixer was
placed approximately ten parts of tap water. Agitation was begun and into
the water was added a polydimethylsiloxane/silica defoamer. The mixture
was agitated until smooth. Into a separate appropriately sized glass
beaker was added about 70 parts of tap water at 120.degree. F. Into the
water was placed slowly with stirring 13 parts of a nonionic block
copolymer (Pluronic F108). The uniform material was cooled and the
silicone emulsion prepared above was mixed slowly into the nonionic
aqueous solution to form the finished rinse aid. The table III following
contains the proportions of the materials used.
TABLE III
______________________________________
2A 2B
______________________________________
Pluronic F108 13 13
Silicone Silica/ 3.3 6.5
Defoamer
Distilled water 83.7 80.5
______________________________________
Using the procedure of Example 1, the compositions set forth in the
following table IV were prepared.
The sheeting test data presented in the following Tables were obtained
using a Champion 1-KAB machine dishwasher having wash and rinse
temperatures of about 160.degree. F. Test pieces were placed in the
machine having a glass door so that they could be observed during the
rinse cycle. For the evaluation, the test pieces were washed in soft water
three times on automatic cycle using 200 grams of an alkaline detergent
prepared by blending 30 wt-% sodium metasilicate, 35% sodium
tripolyphosphate, 3 wt-% Plurafac.RTM. surfactant No. RA-43, and 32%
sodium carbonate. During the three wash cycles no rinse additive was used.
To determine the sheeting effect, the machine was filled with water and
set on manual. Into the water was added 2000 parts of a 2:1 mixture of
margarine and non-fat milk per million parts of rinse water, and a minimum
measured amount of the tested rinse composition. The mixture was
circulated for 3 minutes and the concentration of rinse additive was
progressively increased by injecting increasing amounts of rinse
composition until a substantially continuous sheeting effect of the rinse
water was noted over substantially all the test pieces. The minimum
concentration for continuous sheeting was noted and recorded in the tables
of data.
TABLE IV
______________________________________
SHEETING RESULTS WITH NONIONIC FOOD ADDI-
TIVE SURFACTANTS 1 KAB MACHINE, CITY WATER
SHEETING
RAW TEMP, (Conc. FOAM
MATERIAL F. ppm(a)) Type (b)
(Inch)
______________________________________
RAW MATERIALS (c)
F108 165 150 P 1.0
F127 160 175 P/C 1.5
FORMULATIONS (d)
F108 (15%)
160 175 P/C 1.25
F108 (11.1%)/
164 125 P 3.0
Dioctyl Sodium
Sulfosuccinate
(5.2%)/
Propylene
Glycol
(15.4%)
F127 (15%)/
161 150 P 2.5
Dioctylsodium
Sulfosuccinate
(1.5%)
F108 (15%)/
164 225 C/P 1.25
Lactic Acid
(15%)
F108 (15%)/
159 150 P/C 1.5
Lactic Acid
(10%)
F108 (15%)/
164 150 C/P 1.25
Lactic Acid
(1%)
F108 (15%)/
166 100 P TRACE
Sod Oleate
(2%)
F108 (13%)/
167 125 P TRACE
1520 US (6.5%)
______________________________________
(a) ppm of active components to give sheeting on all substrates;
(b) P = pinhole, C = complete, P/C = mixed;
(c) Materials tested without predilution or formulation; (d) Rest of
formulation consists of water.
The foaming data recorded in the Tables entitled Dynamic Foam Test was
generated in a foam test device which is a cylindrical container 8 liters
in volume, 15 centimeters in diameter and 50 centimeters in height
equipped with an electric hot plate for temperature control, and a pump to
recirculate the test solution at 6 psi via a means to direct a spray of
the test solution onto the surface of the contents of the solution to
generate foam. The rinse aid formulations were added to the water at
160.degree. F. to give a concentration of 100 ppm of sheeting agent. The
foam heights were determined after 1 and 5 minutes of circulation. The
persistence or stability of the foam was also noted. An unstable foam
designated by the letter U, collapsed when the pumping was stopped. Foam
heights less than 3" inches and unstable foam production are preferred.
The data in the Tables demonstrate that the high cloud point nonionic
surfactants can attain sufficient sheeting properties to provide adequate
rinsing of tableware, flatware, etc. at reasonable concentrations between
about 100 and 200 parts of the surfactant per million parts of an aqueous
rinse material. These sheeting properties can be attained at reasonable
operating temperatures and when used with a defoamer can prevent the
generation of stable foam or generation of high levels of foam. The
Pluronic F108 formulations with defoamers exhibited acceptable or no foam
properties.
TABLE V
______________________________________
Dynamic Foam Test
1 2 3 4
______________________________________
Pluronic F108 (BASF)
13.0 13.0 13.0 13.0
1520 US.sup.1 (20% Active)
6.5 6.5 -- --
Keltrol RD.sup.2 0.25 0.5 0.5 0.5
Benzoic Acid 0.05 0.05 0.05 0.05
Sorbic Acid 0.1 0.1 0.1 0.1
Water, Tap, City 80.1 79.85 73.25
81.95
FG 10.sup.1 (10% Active) 13.2
AF.sup.1 (30% Active) 4.4
pH 4.0
______________________________________
Dynamic Foam Test - All At 100 ppm active, 2.3 gm/31.
160.degree. F. 6 psi.
City Water
1 min = 1/2" U.sup.3
1- 5 min = 3/4" U
1 min = 1/2" U
2- 5 min = 3/4" U
1 min = 3/4" U
3- 5 min = 11/2" U
1 min = 3/4" U
4- 5 min = 11/4" U
.sup.1 Polydimethylsiloxane defoamer; Dow Corning
.sup.2 Xanthan gum, Kelco
.sup.3 U = Unstable
The examples and data in Table V show that the nonionic surfactant material
can be combined with silicone defoamers, available xanthan thickeners,
stabilizing agents and other materials and can be diluted to form a useful
rinse aid material. The rinse aid can be diluted with water to form an
aqueous rinse that can be used without the generation of substantial
quantities of foam.
TABLE VI
__________________________________________________________________________
HIGH TEMP RINSE ADDITIVE SHEETING TEST
Pluronic F108 - 13%
1520 US - 6.5%
Keltrol RD - 0.25%
Stainless
Stainless
China
Melamine
Glass
Glass
Steel
Steel
Foam
PPM.sup.1
Temp
Plate
Plate Tumbler
Slide
Knife
Slide
Inches
__________________________________________________________________________
50 160.degree.
-- -- -- -- -- -- --
75 160.degree.
C C -- C P P --
100 161.degree.
C C C C C C Trace
__________________________________________________________________________
.sup.1 Of Pluronic F108
CONDITIONS:
Champion 1KAB machine
Water: Soft (8 ppm hardness)
KEY:
-- No Sheeting
P Pinhole Sheeting
C Complete Sheeting
The data in Table VI demonstrates that a rinse aid containing the nonionic
sheeting agent, a silicone defoamer, and an available thickener can be
combined to form a single phase useful rinse aid. The rinse aid can be
diluted with soft water and can be used in a common automatic warewashing
machine to provide excellent sheeting and low foaming at high temperature
on a variety of ware surfaces including china, melamine plastic, glass and
stainless steel tableware.
The following tables of data further display the excellent low foam
characteristics of the rinse agents of the invention.
TABLE VII
__________________________________________________________________________
Dynamic Foam Tests - Pluronic F108/Silicone Formulations
CONCENTRATION, %(a)
__________________________________________________________________________
F108 14 15 15 13 13 13 13 13 13 13 13 13 13 13
SOD 2 2 2 2
OLEATE
SAG (30% 0.4 1.5 4.5 4.5
770(d)
Active)
1520 US(d)
(20% 1.7 3.3 6.5 3.3 6.5
Active)
FG-10(d)
(10% 6.6 13.2
Active)
AF(d) (30% 2.2 4.4
Active)
Silicone
0 1 3 10 10 3 5 10 5 10 5 10 5 10
Defoamer
ppm(b)
__________________________________________________________________________
FOAM HEIGHT, INCHES (STABILITY)(c)
__________________________________________________________________________
CITY
H.sub.2 O
1 9.5(S)
6.0(S)
4.0(P)
1.75(U)
1.5(P)
1.5(P)
0.75(U)
0.5(U)
0.75(U)
0.75(U)
1.5(U)
0.75(U)
1.5(U)
0.75(U)
MINUTE
5 11.5(S)
9.5(S)
8.5(P)
5.25(P)
2.25(U)
5.0(U)
2.0(U)
1.0(U)
3.25(U)
0.75(U)
5.0(U)
1.5(U)
3.0(U)
0.75(U)
MINUTES
SOFT
H.sub.2 O
1 2.0(U)
1.25(P) 1.0(U) 1.0(U)
0.75(U) 2.0(U)
0.75(U)
MINUTE
5 5.5(P)
3.0(U) 1.25(U) 3.5(U)
1.0(U) 4.5(U)
1.0(U)
MINUTES
__________________________________________________________________________
(a)Rest of formula consists of water;
(b)Level of active silicone defoamer in system at use level of 100 ppm
F108;
(c)160.degree. F., 6 psi, 100 ppm active sheeting agent, S = stable, U =
unstable, P = partially stable foam
(d)All polydimethylsiloxane defoamers. 1520 US, FG10, AF supplied by Dow
Corning; SAG770 supplied by Union Carbide
The examples and the foam test data of Table VIII demonstrate that a stable
single phase rinse aid can be manufactured from the nonionic material
oleate and silicone base defoamers. Such rinse aids can be diluted with
water to form an aqueous rinse that can provide acceptable sheeting and
low foaming properties in city and soft water. The data shows the
combination of a silicone and a oleate base defoamer is particularly good
in defoaming the Pluronic nonionic materials.
While the above description, examples and data provides a basis for
understanding the invention, the invention can be made in a variety of
embodiments. The invention resides in the claims hereinafter appended.
Top